Polyurethane-based anhydrous sizing compositions for glass fibres, glass fibres obtained and composite materials comprising said fibres

ABSTRACT

The invention relates to a sizing composition consisting of a solution comprising less than 5% by weight of solvent and comprising a curable base system, said system comprising at least 50% by weight of a mixture of: one or more components containing at least one isocyanate reactive functional group; one or more components containing at least one hydroxyl reactive functional group; and optionally, one or more components containing at least one amine reactive functional group. A subject of the invention is also the glass strands coated with the aforementioned sizing composition. The glass strands obtained can be used to reinforce organic or inorganic materials.

The present invention relates to a sizing composition for glass strands, to the glass strands obtained and to the composites incorporating said glass strands. More precisely, it relates to an anhydrous sizing composition comprising compounds with isocyanate reactive functional groups and compounds with hydroxyl and/or amine functional groups that are capable of reacting to form polyurethanes and/or polyureas.

The manufacture of glass reinforcing strands is carried out in a known manner using molten glass streams emanating from the orifices of bushings. These streams are drawn in the form of continuous filaments, and then these filaments are brought together as base strands that are then collected in various forms: bobbins of continuous strands, continuous- or chopped-strand mats, chopped strands, etc.

Before they are brought together in the form of strands, the filaments are coated with a size by being passed them over a sizing member. The application of a size is necessary, on the one hand, for obtaining strands and, on the other hand, for producing composites that combine said strands as reinforcing agent with other organic and/or inorganic materials.

The size serves in the first place as a lubricant and protects the strands from the abrasion resulting from high-speed friction of the strands on the various members encountered in the aforementioned process. It is important for the glass strand to possess a slippability (or “slip”) sufficient to withstand the subsequent conversion operations, such as unwinding from and winding onto appropriate supports, or weaving, so as to minimize any friction liable to break the filaments.

The size also has the function of giving the aforementioned strands integrity, that is to say of binding the filaments together within the strands. This integrity is more particularly desirable in textile applications in which the strands are subjected to high mechanical, especially tensile, stresses. Thus, when the filaments are poorly bonded together, they have a tendency to break more easily when they are stressed, resulting in the formation of fuzz that disrupts the operation of the textile machines, or even requires them to be completely shut down. In addition, non-integral strands are considered as being tricky to handle, especially when they are to be used to form bobbins, as broken filaments then appear along the sides. Apart from the unsatisfactory esthetic appearance, it is more difficult to unwind the strands removed from these packages.

The size also has the role of promoting the wetting and/or impregnation of the strands with the materials to be reinforced, by creating bonds between the strands and these materials. The quality of the adhesion of the material to the strands and the wettability and/or impregnability of the strands by the material depend on the mechanical properties of the resulting composites. In most cases, the size makes it possible to obtain composites having improved mechanical properties.

The sizing compositions must also be compatible with the strand production conditions that in particular impose high filament drawing rates, which may be up to several tens of meters per second. They must also withstand the shear forces induced by the passage of the filaments, especially as regards the viscosity, which must not appreciably fluctuate, and be capable of correctly wetting the surface of the filaments so as to obtain uniform sheathing over their entire length.

Sizing compositions that contain components capable of curing after being deposited on the glass must furthermore remain stable at the temperatures (around 60 to 100° C.) beneath the bushing. In particular, it is desirable to ensure that the curable constituents possess a low vapor pressure at the temperatures indicated, so as to avoid any problem of a concentration variation resulting from the volatilization of certain constituents. It is also important to control the degree of conversion defined by the ratio of the number of functional groups that have reacted in the size to the number of initial reactive functional groups in order to guarantee that sized glass strands of constant quality are obtained. The degree of conversion must especially be very close to the expected theoretical value in order to prevent the size from changing over time.

As a general rule, the sizing compositions are chosen so as to fulfill the aforementioned functions and so as not to undergo chemical reactions causing a substantial increase in the viscosity, both during storage at room temperature and under the higher temperature conditions beneath the bushing.

The sizes most commonly employed are low-viscosity aqueous sizes. Although very easy to use, they do have disadvantages. In particular, these sizes contain a very large proportion of water, generally more than 80%, the water having to be removed after deposition on the glass since water results in a reduction in adhesion between the strands and the material to be reinforced. A well-known means consists in drying the glass strands thermally, but this is a lengthy and expensive operation that needs to be matched perfectly to the strand manufacturing conditions. Moreover, this treatment is not neutral with respect to the strand. In particular, when the sized strand is in the form of packages, what may occur is a change in the distribution of the constituents of the size, by irregular and/or selective migration, a coloration of the strand and a deformation of the package.

Aqueous sizing compositions containing polyurethanes have already been proposed. Thus, EP-A-0 554 173 discloses a size intended for coating glass strands used in the construction of molded composites, the bonding agent of which is formed from one or more polyurethane resins, optionally combined with one or more polyepoxides. JP-2000044793 proposes the reinforcement of thermoplastics by means of glass strands treated with a sizing composition comprising a polyurethane resin in emulsion, a coupling agent and a lubricant.

Moreover, “anhydrous” sizing compositions are known, that is to say those comprising less than 5% by weight of solvent and consisting of a base system formed from curable components.

In FR-A-2 727 972, the sizing composition is capable of curing under the action of UV radiation or an electron beam. The curable base system contains at least one component of molecular mass less than 750, having at least one epoxy functional group and comprising at least 60% by weight of one or more components of molecular mass less than 750 having at least one epoxy, hydroxyl, vinyl ether, acrylic or methacrylic functional group.

FR-A-2 772 369 discloses a sizing composition for glass strands that does not require a heat treatment step after deposition on the strand. It comprises at least 60% by weight of components capable of curing, these components being, in the case of at least 60% of them, components of molecular mass less than 750 and these curable components comprising at least one mixture of one of more components having at least one acrylic and/or methacrylic reactive functional group and of one or more components having at least one primary amine and/or secondary amine functional group, at least 20% by weight of these components possessing at least two acrylic, methacrylic, primary amine and/or secondary amine reactive functional groups.

One object of the present invention is to propose a thermally curable anhydrous sizing composition for coating glass strands, which involves the reaction of one or more compounds containing one or more isocyanate functional groups and one or more compounds containing one or more hydroxyl functional groups and, optionally, of one or more compounds containing one or more amine functional groups.

Another object of the present invention is to propose a sizing composition in which the reaction time of the curable system may range, in order to be adapted to the application conditions, from a system able to crosslink relatively slowly, in one or a few hours, to an extremely reactive system having a gel time of around ten minutes.

Another object of the invention is to propose a sizing composition that makes it possible to control the texture of the glass strands, that is to say their stiffness and their integrity.

Another object of the invention is to propose glass strands coated with a size that makes them suitable for undergoing an operation for increasing their volume (“bulking” operation).

The sizing composition according to the invention consists of a solution comprising less than 5% by weight of solvent and comprising a curable base system, said system comprising at least 50% by weight of a mixture of:

one or more components containing at least one isocyanate reactive functional group;

one or more components containing at least one hydroxyl reactive functional group; and

optionally, one or more components containing at least one amine reactive functional group.

In the present invention, the expressions below have the following meanings:

“solvent” is understood to mean water and organic solvents capable of being used to dissolve certain curable components. The presence of one or more solvents in a limited amount does not require any particular treatment in order to remove them. In most cases, the sizes according to the invention are completely free of solvent;

“cure”, “curable”, “curing”, etc. are understood to mean “cure and/or crosslink”, “curable and/or crosslinkable”, “curing and/or crosslinking”, etc., respectively;

“reactive functional group” is understood to mean a functional group that can act in the size curing reaction, it being possible for the curing to take place at the usual strand production temperature (around 20 to 100° C.) with no additional supply of energy, or else at a higher temperature, up to about 150° C. (thermal curing); and

“curable base system” is understood to mean the combination of essential components that allow the expected polyurethane/polyurea structure of the size to be obtained.

Hereafter, the expressions “one or more isocyanate components”, “one or more hydroxyl components” and “one or more amine components” are understood to mean “one or more components containing at least one isocyanate reactive functional group”, “one or more components containing at least one hydroxyl reactive functional group” and “one or more components containing at least one amine reactive functional group”, respectively.

The sizing composition according to the invention is compatible with the glass strand production conditions imposed by the direct process, the viscosity of the composition being adapted according to the draw speed and the diameter of the filaments made to pass through the sizing composition. As a general rule, it is desirable for the viscosity not to exceed 400 mPa·s, preferably 150 mPa·s, so that the sizing composition can be uniformly distributed over the surface of the glass filaments. The composition according to the invention also has a strand wetting rate compatible with the strand draw rate.

As a general rule, the curable base system represents 50 to 100% by weight of the sizing composition according to the invention, mainly 60 to 100% by weight of the composition and, in most cases, 75 to 90% by weight of the composition.

The base system consists predominantly (preferably 75% by weight and up to 100% by weight in most cases) of one or more isocyanate components and one or more hydroxyl components, and where appropriate one or more amine components, the use of this mixture of components allowing polyurethane or poly(urethane-urea) polymers to be obtained by the reaction of the various isocyanate, hydroxyl and amine functional groups of the initial constituents. It is these polymers that predominantly participate in the structure of the size, and it is from this structure that the properties of the sized glass strands directly stem.

Furthermore, the base system comprises a majority (preferably at least 70% by weight and better still at least 80% by weight) of one or more components of molecular mass less than 750, this component or these components normally forming part, in most cases, of the aforementioned isocyanate, hydroxyl and amine components.

Preferably, and in general according to the invention, the aforementioned components of molecular mass less than 750 are of molecular mass less than 600.

When the base system contains components of molecular mass less than 750, it advantageously includes one or more isocyanate and/or hydroxyl and/or amine components of molecular mass greater than 1000 (prepolymers). The total content of these components is generally less than 20% by weight of the sizing composition, preferably less than 15%, as above this content the viscosity and the reactivity of the composition become too high to allow the size to be deposited on the glass strands under the conditions of the abovementioned process.

In general, the reactivity of the base system is varied in order to be adapted to the application conditions. In particular, the gel time has a major influence on the size deposition quality and on the construction of the packages when the strand is collected in the form of bobbins. The gel time must not be less than about 10 minutes in order to allow the size to be deposited beneath the bushing by means of sizing rolls with no significant risk of the size gelling on the rolls. Moreover, the gel time must not exceed 1.5 hours so that it is possible to obtain strand packages that can be handled on leaving the winder. Gel times varying from 15 to 45 minutes prove to be very satisfactory.

According to certain embodiments, the base system according to the invention may optionally include a small proportion (less than 20%) of one or more components participating in the structure of the cured size, but having no isocyanate, hydroxyl or amine functional groups and/or a molecular mass greater than or equal to 1000. Preferably, the proportion of these components is less than 15%.

According to the preferred embodiment of the invention, which allows particularly satisfactory results to be obtained, the base system consists of one or more isocyanate components containing at least two isocyanate reactive functional groups, one or more hydroxyl components containing at least one hydroxyl reactive functional group and, optionally, one or more components containing at least one amine reactive functional group. Particularly advantageously, the base system consists either of one or more isocyanate components containing three isocyanate reactive functional groups and one or more hydroxyl components containing one to three hydroxyl reactive functional groups, or one or more isocyanate components containing three isocyanate reactive functional groups, one or more hydroxyl components containing a hydroxyl reactive functional group and one or more amine components containing two primary amine reactive functional groups.

According to the invention, all or some of the hydroxyl components of the base system may contain one or more hydroxyl reactive functional groups and one or more amine reactive functional groups.

The isocyanate component or components of the base system may especially be chosen from:

-   -   aliphatic or cycloaliphatic isocyanates, such as hexyl         isocyanate, dodecyl isocyanate, hexadecyl isocyanate, cyclohexyl         isocyanate, 1-adamantyl isocyanate, 1,6-hexamethylene         diisosyanate (HDI), 1,12-dodecamethylene diisocyanate,         isophorone diisocyanate (IPDI),         1,1-methylenebis(4-isocyanatocyclohexane) (HMDI),         transcyclohexane 1,4-diisocyanate (CHDI), esters, such as butyl         isocyanatoacetate and 3-ethyl isocyanatopropionate, or ethers,         such as trifluoroacetyl isocyanate;     -   aromatic isocyanates, such as 3,5-dimethylphenyl isocyanate,         4-methoxybenzyl isocyanate, 4-dimethylaminophenyl isocyanate,         4-methoxyphenyl isocyanate, 4-ethoxyphenyl isocyanate, xylylene         diisocyanate (XDI), toluene diisocyanate (TDI),         naphthalene-1,5-diisocyanate (NDI), 4,4′-diphenylmethane         diisocyanate (MDI) and tetramethylxylene diisocyanate (TMXDI);         and     -   isocyanate-terminated prepolymers (NCO-prepolymers), for example         TOLONATE® HDT and TOLONATE® HDB (NCO content: 20-25%; sold by         Rhodia), products resulting from the reaction between polyethers         and isocyanates, such as polytetramethylene glycol/TDI         prepolymers, for example CASTOMER® E 1009 and CASTOMER® E 1004         (NCO content:

4.2 and 9.3% respectively; sold by Baxenden); polypropylene glycol/TDI prepolymers, for example TRIXENE® DP9B/1534 (NCO content: 4.4%; sold by Baxenden) and products resulting from the reaction between polyesters and isocyanates, especially TDI, for example CASTOMER® DP9A/956 (NCO content: 4%; sold by Baxenden).

Among the isocyanates that have just been mentioned, some are monomers whose vapor pressure is relatively high, making them potentially toxic to humans. This is why isocyanates in the form of prepolymers of molecular mass at least equal to 400 and preferably at least equal to 450 are preferred. Advantageously, the molecular mass is less than or equal to 2000, preferably less than or equal to 1200, since above this the prepolymers have a high melting point or a high viscosity, which make the sizing composition difficult to apply to the glass filaments. Advantageously, the prepolymer has a content of free isocyanate reactive functional groups (NCO content) at least equal to 3%, preferably less than 25% and advantageously greater than or equal to 5%.

As a general rule according to the invention, the proportion of isocyanate component(s) in the base system represents 15 to 75%, and preferably 30 to 60%, by weight. Preferably, at least 10% of the isocyanate components are polyisocyanates, and advantageously 100% of the isocyanate components are polyisocyanates.

The content of isocyanate component(s) in the composition is generally between 10 and 50% and preferably between 20 and 40% by weight.

The hydroxyl component or components of the base system may be chosen from:

-   -   aliphatic or cycloaliphatic alcohols, such as hexanol, octanol,         dodecanol, cyclohexanol, 1,2-propanediol,         2-ethyl-2-hydroxymethyl-1,3-propanediol, butanediol, butenediol,         pentanediol, hexanediol, cyclohexandiol,         1,4-cyclohexanedimethanol, glycerol, trimethylolpropane and         pentaerythritol;     -   tertiary alkanolamines, such as 2-(diisopropylamino)ethanol,         3-dimethylamino-1-propanol, 3-diethylamino-1,2-propanediol,         3-diisopropylamino-1,2-propanediol, N-butyl-diethanolamine,         triethanolamine and triisopropanolamine,     -   monohydroxylated components of the hydroxyl-terminated polyester         type, obtained by reaction between a fatty acid and a         poly(alkylene oxide), such as polyethylene glycol isostearate or         polypropylene glycol isostearate, components of the         hydroxyl-terminated polyether type obtained by reaction between         a fatty alcohol and ethylene oxide and/or propylene oxide, for         example lauric alcohol having 4 ethylene oxide units, or by         reaction between an alkyl phenol and ethylene oxide and/or         propylene oxide, for example nonyl phenol having 8 ethylene         oxide units; and     -   poly(oxyalkylene)polyols, for example poly(oxyethylene)polyols,         poly(oxypropylene)polyols,         poly(oxyethylene)(oxypropylene)polyols,         poly(tetrahydrofuran)polyols and poly(caprolactone)polyols, the         molecular mass of which is preferably less than 1500.

Among the hydroxyl compounds that have just been mentioned, those containing more than 5 carbon atoms are preferred. Compounds having a smaller number of carbon atoms may be employed when it is desired to lower the viscosity of the base system and/or to limit the chain length during curing.

Preferably according to the invention, the hydroxyl components are chosen from alcohols containing at least two hydroxyl reactive functional groups, and better still two or three hydroxyl functional groups.

As indicated above, the hydroxyl components may include one or more amine functional groups. Examples of such components are given later.

Within the context of the invention, it is also possible to use, as hydroxyl components, components containing one or more epoxide functional groups, the epoxy ring of which may be opened by the action of a catalyst in order to generate a secondary hydroxyl. The catalyst that can be used for this purpose may be any catalyst known to those skilled in the art, as indicated later.

As examples of such components, mention may be made of components containing an epoxy functional group such as cyclohexene monoxide, glycidyl ethers, particularly C₄-C₂₀ alkyl glycidyl ethers, phenyl glycidyl ether, alkyl phenyl glycidyl ethers, monoglycidyl ethers of derivatives of bisphenol A, especially of acryloxybisphenol A, and components containing several epoxy functional groups, such as polyglycidyl ethers, in particular 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, resorcinol diglycidyl ether, bisphenol A or bisphenol F diglycidyl ether, polybutadiene diglycidyl ether, polyglycol diepoxydes, trimethylolpropane triglycidyl ether and polyglycidyl ethers of alkyl polyesters.

As a general rule according to the invention, the proportion of hydroxyl component(s) varies from 15 to 60%, and preferably 20 to 50%, by weight of the base system. Preferably, at least 15%, and advantageously at least 20%, of the hydroxyl component(s) are components comprising at least two hydroxyl reactive functional groups.

The content of hydroxyl component(s) in the composition is generally between 15 and 55%, and preferably between 25 and 45%, by weight.

The number of reactive sites of the hydroxyl components that can react with the reactive sites of the isocyanate components may vary greatly. In general, the ratio r of the number of isocyanate reactive sites to the number of hydroxyl reactive sites varies from 0.1 to 6 and preferably from 0.3 to 4, it being understood that an isocyanate functional group counts as one isocyanate reactive site and that a hydroxyl functional group counts as one hydroxyl reactive site.

The amine component or components of the base system may be chosen from components containing one or more primary and/or secondary amine functional groups, such as components having linear, branched or cyclic hydrocarbon chain components, for example, N,N-dibutylamine, N,N-dicyclohexylamine, aminoethylpiperazine, 2(2-aminoethoxy)ethanol, 3-amino-1-propanol, 2-amino-2-ethyl-1-propanol, N-(2-aminoethyl)ethanolamine, 2-amino-2-ethyl-1,3-propanediol, aromatic components, for example 1,3-diphenylguanidine and 3,4-diaminotoluene, and amine-terminated polymers, for example (polybutadiene)diamine. According to the invention, some of the aforementioned amine compounds contain one or more hydroxyl functional groups as mentioned above.

Preferably, the amine components are chosen from components containing at least two primary and/or secondary amine functional groups. So as to reduce the reactivity of the amine compounds, it may be envisaged to add a small amount (around 2 to 15% by weight of the composition) of a ketone, in particular a diketone such as pentanediene, dibenzoylmethane, 2,2,6,6-trifluoro-3,5-heptanedione, dimethyl-1,4-cyclohexanedione-2,5-dicarboxylate, 4,4,4-trifluoro-1-(2-naphtyl)-1,3-butanedione, thenoyltrifluoroacetone, 2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedione, 3-methyl-2,4-pentanedione, 1-(2-furyl)-1,3-butanedione and 2,6-dimethyl-3,5-heptanedione. Pentanedione, dibenzoylmethane, 3-methyl-2,4-pentanedione and 2,6-dimethyl-3,5-heptanedione are preferred.

As a general rule according to the invention, the proportion of amine component(s) represents 0 to 30% by weight of the base system and in most cases it is between 5 and 30%.

The content of amine component(s) in the composition is generally between 0 and 30%, and preferably between 0 and 20%, by weight.

The number of reactive sites of the amine components that can react with the reactive sites of the isocyanate components may vary greatly. As a general rule, the ratio r′ of the number of isocyanate reactive sites to the sum of the number of hydroxyl reactive sites and of the number of amine reactive sites varies from 0.1 to 6, and preferably from 0.3 to 4, it being understood that an isocyanate functional group counts as one isocyanate site, that a hydroxyl functional group counts as one hydroxyl reactive site, that a primary amine functional group counts as two amine reactive sites and that a secondary amine functional group counts as one amine reactive site.

The sizing composition may include, in addition to the base system, at least one catalyst promoting size curing. This may, for example, be a specific catalyst for the synthesis of polyurethanes, such as 1,4-diazabicyclo[2.2.2]octane and 1,8-diazabiscyclo[5.4.0]undec-7-ene, or else a catalyst suitable for epoxy components, such as tris(N,N-dimethylaminomethyl)benzene, tris(N,N-dimethylaminopropyl)triazine, N,N-dimethylbenzylamine and 2-propylimidazole.

The content of components acting only as catalysts for the base system (that is to say those not participating in the structure of the cured size) is generally less than 5% by weight of the sizing composition, preferably less than 3% and in most cases around 0.5% by weight.

The sizing composition may also include, within the limits indicated above, a solvent for helping to dissolve certain components of the base system. As examples of such a solvent, mention may be made of ethyl acetate, N-methyl pyrrolidone and tetrahydrofuran.

The sizing composition may include one or more components (hereafter called additives) in addition to the aforementioned components that essentially participate in the structure of the cured size, and where appropriate to the catalysts and to the solvent. These additives give the size particular properties and, when the composite is deposited in two steps, as is preferred, they may be provided by one or both of the constituent compositions of the size.

The composition according to the invention may include, as additive, at least one coupling agent for bonding the size to the glass. The coupling agent may be a component of the base system, in which case it participates in the curing reaction, or a component acting only as additive.

The proportion of coupling agent(s) is generally between 0 and 30% by weight of the sizing composition and in most cases is greater than 5% by weight. Preferably, it is between 10 and 25% of the composition.

The coupling agent is generally chosen from silanes such as γ-glycidoxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, poly(oxyethylene/oxypropylene)trimethoxysilane, γ-aminopropyltriethoxysilane, vinyltrimethoxysilane, phenylaminopropyltrimethoxysilane, styrylaminoethylaminopropyltrimethoxysilane or terbutylcarbamoylpropyltrimethoxysilane, siloxanes, titanates, zirconates and mixtures of these compounds. Preferably, silanes are chosen.

The composition may include, as additive, at least one textile processing aid acting essentially as lubricant, and it is in many cases necessary for the composition to have the functions of a size.

The proportion of textile processing aid is generally between 0 and 30%, preferably between 3 and 20%, by weight of the composition.

The textile processing aid is generally chosen from optionally alkoxylated fatty esters, such as decyl laurate, isopropyl palmitate, cetyl palmitate, isopropyl stearate, isobutyl stearate, trimethylolpropane trioctanoate, trimethylolpropane tridecanoate, alkyl phenol derivatives, such as ethoxylated nonyl phenol, optionally alkoxylated fatty alcohols, such as methyl-terminated polyethylene glycol laurate or stearate advantageously containing fewer than 10 oxyethylene units, mixtures based on mineral oils, and mixtures of these compounds. The processing aids are preferably free of functional groups liable to act preferentially with isocyanate, hydroxyl and/or amine functional groups.

The composition according to the invention may be deposited on the glass filaments in one or more steps.

When they are deposited in one step, all of the curable constituents are contained in the sizing composition and it is then imperative to block either the isocyanate functional groups or the hydroxyl and amine functional groups so as to prevent the composition from curing prematurely before it is deposited on the glass filaments. The preferred solution in this embodiment consists in using polyisocyanates whose isocyanate reactive functional groups are blocked by protective groups, it being possible for the functional groups to be unblocked by the addition of an unblocking agent. As examples of such polyisocyanates, mention may be made of derivatives of TDI, HDI, IPDI, and MDI (for example sold by Baxenden under the references BI 7673, BI 7772, BI 7950, BI 7962, BI 7983, BI 7960, which may be unblocked by 3,5-dimethylpyrazole).

The composition according to the invention is preferably deposited in several steps, for example under the conditions of the process described in FR-A-2 763 328. In that process, molten glass streams flowing out of orifices placed at the base of one or more bushings are drawn into the form of one or more sheets of continuous filaments and then the filaments are brought together as one or more strands that are collected on one or more moving supports. The size is deposited by applying to the filaments a first stable composition of viscosity between 0.5 and 300 mPa·s and at least one second stable composition of viscosity between 0.5 and 250 mPa·s, supplied separately from the first composition.

The second composition may be deposited on the filaments as soon as possible after the first composition has been deposited or on the strands as late as possible during their collection on the supports. The difference in viscosity between the compositions is generally less than 150 mPa·s.

The composition according to the invention is preferably applied in two steps, the first composition preferably comprising the polyisocyanate component(s) and optionally one or more additives, and the second composition comprising the hydroxyl component(s) and/or the amine component(s) and optionally one or more additives, especially the curing catalyst or catalysts.

Deposition of the size in two steps is particularly advantageous. It allows better control of the curing reactions and consequently the size has a uniform quality over the entire length of the strands, while ensuring a high productivity with less risk of the strands breaking.

As a general rule, the size deposited on the strand requires no additional supply of energy for it to cure. However, it is possible to subject the strand, after fiberizing, to a heat treatment at various stages in the process for the purpose of accelerating the curing reaction. This treatment may be applied to strands collected in the form of a package, to sheets of continuous or chopped strands, or else to strands in combination with an organic material for producing composites. As an illustration, for a roving weighing about 20 kg, a treatment at a temperature of around 120 to 140° C. for about 8 hours proves to be satisfactory. For chopped strands, the treatment time does not exceed around ten minutes at an equivalent temperature.

The actual integrity of the strands through the binding together of the constituent filaments that is obtained after the size has cured is particularly important when the amount of size on the strands is relatively low. The loss on ignition of the strands coated with the sizing composition according to the invention does not in fact exceed 3% by weight, preferably 1.5% and advantageously 0.8% by weight.

The sized strands are generally collected in the form of packages on rotating supports, such as cakes, rovings and cops. Whatever the state of cure of the size and the crossing angle, even when the latter is small (less than 1.5°), it is easy to unwind the strands from the packages and handle them. Straight-sided packages retain their dimensional characteristics over time and undergo no deformation. The strands may also be used subsequently for producing meshes, fabrics, braids, tapes, etc.

The strands may also be collected on receiving supports moving in translation. In particular, they may be thrown, by a member that also serves to attenuate them, toward the collecting surface moving transversely to the direction of the thrown strands, for the purpose of obtaining a web of intermingled continuous strands or mat. The strands may also be chopped before collection by a member serving also to attenuate them.

The presence of polyurethane or poly(urethane-urea) polymers in the size provides a certain flexibility in the bonding and allows the filaments to be able to move relative to one another. In this way, the integrity of the glass strands is improved. The strands coated with the size according to the invention prove to be particularly advantageous for producing fabrics or for applications requiring them to be chopped, such as in the simultaneous spray molding technique. Another advantage due directly to the presence of the aforementioned polymers is that the strands have a better impact strength than other sized strands, while remaining compatible with many of the thermoplastics to be reinforced.

The sized glass strand according to the invention is noteworthy in that it can be treated so as to increase its volume and obtain what is commonly called a “bulked” strand. The treatment consists in making the strand pass through a system comprising one or more nozzles through which a flow of air passes, then in collecting the strand in the form of a package on a suitable device. This strand can then be woven in particular to form wall fabrics to be painted.

The glass filaments constituting these strands have a diameter that can vary widely, usually from 5 to 30 μm. They may be made of any glass whatsoever, the most common in the field of reinforcing strands being E-glass and AR-glass.

The strands obtained according to the invention may advantageously be used to reinforce various materials for the purpose of obtaining composites having high mechanical properties. The composites are obtained by combining at least the glass strands according to the invention with at least one organic and/or inorganic material, the glass content in the final composite generally varying from 1 to 5% by weight (cementicious matrix) and from 20 to 80%, preferably 30 to 70%, by weight (organic matrix).

The examples that follow allow the invention to be illustrated without, however, limiting it. In these examples, the following analytical methods are used for measuring the physical properties.

In the case of sizing compositions:

-   -   the viscosity is measured by means of a SOFRASER MIVI 4000         apparatus sold by Sofraser. It is expressed in mPa·s;     -   the gel time, expressed in minutes, is measured on the mixture         of compositions A and B by means of a TROMBOMAT device (sold by         Prodemat S.A.), which plots the curve of the viscosity of the         sizing composition as a function of time. On this curve, the         point of intersection of the tangent at the point of inflexion         and the x-axis corresponds to the gel time.

In the case of strands coated with the sizing composition according to the invention:

-   -   the loss on ignition is measured according to the ISO 1887         standard. It is expressed in %;     -   the amount of fuzz allows the abrasion resistance of a strand to         be assessed. It is measured by weighing the amount of material         that becomes detached from the strand after it passes over a         series of eight ceramic cylindrical turn rolls arranged in such         a way that the angle of deflection of the strand at each turn         roll is equal to 90°. The amount of fuzz is given in mg per 1 kg         of strand tested;     -   the stiffness or rigidity is measured under the conditions         defined by the ISO 3375 standard, on ten specimens before and         after undergoing the abovementioned abrasion resistance test.         The stiffness is expressed in mm and denoted by x(y), x and y         that represent the value measured before and the value measured         after the strand passes over the turn rolls, respectively. The         value y allows the integrity of the strand, and indirectly its         ability to be impregnated with a material, more particularly a         polymer-type organic material, to be pre-assessed. In general, a         sized strand whose y value is less than 100 mm, and preferably         close to 60 mm (the lowest value that can be obtained) is used         more for applications requiring good impregnation by the matrix.         A strand having an x value greater than or equal to 120 and a y         value of greater than or equal to 100 is suitable for a use         requiring high strand integrity, for example for weaving, and         optionally in the case of chopping;     -   the tensile strength is measured under the conditions defined by         the ISO 3341 standard. It is expressed in g/tex.

For composites containing glass strands coated with the sizing composition:

-   -   the flexural strength and the flexural modulus are measured         under the conditions defined by the ISO 178 standard, before and         after aging by immersion in water at 100° C. for 24 hours         (polyester resin composites) and 72 hours (epoxy resin         composites). It is expressed in MPa;     -   the shear strength is measured under the conditions defined by         the ISO 4585 standard, before and after aging by immersion in         water at 100° C. for 24 hours (polyester resin composites) and         72 hours (epoxy resin composites). It is expressed in MPa.

EXAMPLE 1

Filaments 13.6 μm in diameter obtained by drawing strands of molten E-glass flowing from a bushing (800 orifices) were coated with a first composition A and then with a second composition B (in percentages by weight): Composition A triisocyanate⁽¹⁾ 35 γ-methacryloxypropyltrimethoxysilane⁽²⁾ 10 γ-glycidoxypropyltrimethoxysilane⁽³⁾ 10 isopropyl palmitate 5 Composition B 1,5-pentanediol 15 3-dimethylamino-1-propanol 11.5 polyethyleneglycol isostearate⁽⁴⁾ 13 1,4-diazabicyclo[2.2.2]octane 0.5

Compositions A and B had a viscosity of 49 mPa·s (at 21° C.) and 58 mPa·s (at 22.5° C.), respectively.

Parallel with the sizing of the filaments, a mixture containing equal parts of compositions A and B was produced. The mixture had a viscosity of 1000 Pa·s after one hour and a gel time of 21 minutes.

The ratios r and r′ of the sizing composition had the same value: 0.487.

The filaments were brought together to form a strand that was wound on a rotating support so as to obtain a direct roving of 14 kg. The strand had a linear density of 297 tex and a loss on ignition of 0.65%.

This strand had a tensile strength equal to 38.7 g/tex, a stiffness equal to 162 mm (122 mm) and an amount of fuzz equal to 8 mg.

From the strand thus obtained, two series of composite panels having parallel strands were produced according to the ISO 9291 standard using two different resins. The first resin was an epoxy resin consisting of 100 parts by weight of epoxy resin⁽⁵⁾, 90 parts by weight of phthalic anhydride⁽⁶⁾ and 0.5 parts by weight of tertiary amine⁽⁷⁾. The second resin was an unsaturated polyester resin consisting of 100 parts by weight of isophthalic polyester⁽⁸⁾ and 1.5 parts by weight of peroxide⁽⁹⁾.

The values of the mechanical properties of these composites are given below: Epoxy resin Polyester resin Flexural strength (MPa) Before treatment 2555.6 2738.4 After treatment 2039.9 1718.2 Flexural modulus (MPa) Before treatment 39982 37051 After treatment 37957 35339 Shear strength (MPa) Before treatment 67.3 45.4 After treatment 47.3 25.8

Although the abovementioned mechanical properties are inferior to those that may be obtained with known aqueous sizing compositions especially suitable for epoxy or polyester resins, they are, however, significant. Their level of performance is average, comparable to that of most current strands, and in any case it remained satisfactory for the applications envisioned here.

EXAMPLE 2

In this example, the conditions of Example 1 were repeated, using the following: Composition A trilsocyanate⁽¹⁾ 35 γ-methacryloxypropyltrimethoxysilane⁽²⁾ 10 γ-glycidoxypropyltrimethoxysilane⁽³⁾ 10 isopropyl palmitate 5 Composition B polyglycol (molecular mass MW = 1000)⁽¹⁰⁾ 15 3-dimethylamino-1-propanol 11.5 polyethyleneglycol isostearate⁽⁴⁾ 13 1,4-diazabicyclo[2.2.2]octane 0.5

Parallel with sizing of the filaments, a mixture containing equal parts of compositions A and B was produced. The mixture had a viscosity of 2000 Pa·s after 1 hour and a gel time of 20 minutes.

Compositions A and B had a viscosity of 49 cP (at 21° C.) and 68 cP (at 22.5° C.), respectively.

The ratios r and r′ of the sizing composition had the same value: 0.998.

The filaments were brought together to form a strand that was wound on a rotating support so as to obtain a direct roving of 14 kg. The strand had a linear density of 286 tex and a loss on ignition of 0.76%.

This strand had a tensile strength equal to 34.5 g/tex, a stiffness equal to 157 mm (110 mm) and an amount of fuzz equal to 5 mg.

EXAMPLE 3

In this example the conditions of Example 1 were repeated, using the following compositions A and B: Composition A triisocyanate⁽¹⁾ 35 γ-methacryloxypropyltrimethoxysilane⁽²⁾ 10 γ-glycidoxypropyltrimethoxysilane⁽³⁾ 10 isopropyl palmitate 5 Composition B 1,5-pentanediol 18 N-butyldiethanolamine 11 polyethylene glycol (molecular mass MW = 300) 10 1,4-diazabicyclo[2.2.2]octane 1

Compositions A and B had a viscosity of 49 cP (at 21° C.) and 58 cP (at 22.5° C.), respectively.

The ratios r and r′ of the sizing composition had the same value: 0.375.

Parallel with sizing of the filaments, a mixture containing equal parts of compositions A and B was produced. The mixture had a viscosity of 60 Pa·s after 1 hour and a gel time of 26 minutes.

A strand of 287 tex linear density was formed and collected on a series of bobbins. This strand underwent a “bulking” treatment under the following conditions: the strands extracted from two bobbins were brought together and made to pass in succession over a first drawing godet (speed: 220 m/min), through a nozzle (inlet and outlet diameters of 0.7 and 2.2 mm, respectively; air pressure: 6-6.5 bar), over a second draw godet (speed: 183.5 m/min) and finally over a winding device (pressure: 2.5 bar).

The strand obtained had a linear density of 640 tex, a stiffness before the turn roll of 110 mm, a loss on ignition of 0.21% and it left no visible sticky deposit.

The strand obtained had sufficient tensile strength to be able to be woven. The fabric formed had a good “coverage” (was “closed”), was highly hydrophobic and possessed good impregnabability by polyvinyl acetate (loss on ignition about 17%). It could be used as cloth to be painted.

EXAMPLE 4

In this example, the conditions of Example 1 were repeated, using the following: Composition A triisocyanate⁽¹⁾ 35 γ-methacryloxypropyltrimethoxysilane⁽²⁾ 10 γ-glycidoxypropyltrimethoxysilane⁽³⁾ 10 isopropyl palmitate 5 Composition B polyethylene glycol isostearate⁽⁴⁾ 9 etherified lauric alcohol (4 ethylene oxide units)⁽¹²⁾ 9.5 triethanolamine 17 1,4-diazabicyclo[2.2.2]octane 0.5 1-methyl-2-pyrrolydinone 4

The ratios r and r′ of the sizing composition have identical values of 0.589.

Parallel with the sizing of the filaments, a mixture consisting of equal parts of compositions A and B was produced. The mixture had a viscosity of 2800 Pa·s after 1 hour and a gel time of 32 minutes.

The filaments were brought together into 51 tex strands that were wound as cakes. From the strands extracted from 24 cakes, a 1400 tex strand having a loss on ignition of 1.28% was formed.

The strand had moderate integrity and a moderate stiffness and could be easily chopped. Its ability to be impregnated with a polyester resin was evaluated to be 1, measured visually on a scale ranging from 0 (poor; absence of wetting) to 5 (excellent; strand invisible in the resin).

The strand could be used as reinforcement in materials of the SMC (sheet molding compound) type.

EXAMPLE 5

Filaments 14 μm in diameter obtained by drawing molten strands of E-glass flowing from a bushing (800 orifices) were coated with a first composition A and then with a second composition B (in percentages by weight): Composition A triisocyanate⁽¹⁾ 35 γ-methacryloxypropyltrimethoxysilane⁽²⁾ 15 isopropyl palmitate 7 1-methyl-2-pyrrolydinone 3 Composition B etherified lauric alcohol (4 ethylene oxide units)⁽¹²⁾ 16 polybutadienediamine (molecular mass = 1200)⁽¹³⁾ 15 isopropyl palmitate 8 1,8-diazabiscyclo[5.4.0]undec-7-ene 1

The ratios r and r′ of the sizing composition were 4.71 and 3.01, respectively.

Parallel with sizing of the filaments, a mixture consisting of equal parts of compositions A and B was produced. The mixture had a viscosity of 716 Pa·s after 1 hour and a gel time of 10.5 minutes.

The filaments were brought together to form a strand that was wound on a rotating support so as to obtain a direct roving of 20 kg. The strand had a linear density of 315 tex and a loss on ignition of 0.57%. It possessed a tensile strength equal to 31.3 g/tex, a stiffness equal to 170 mm (80 mm) and an amount of fuzz equal to 1.6 mg.

The strand thus obtained was woven and the fabric used for reinforcing epoxy, polyester and phenolic matrices.

(1) Sold under the reference TOLONATE HDT LV by Rhodia;

(2) Sold under the reference SILQUEST A 174 by Witco-Crompton;

(3) Sold under the reference SILQUEST A 187 by Witco-Crompton;

(4) Sold under the reference LDM 1018 by Seppic;

(5) Sold under the reference LY 556 by Ciba-Geigy;

(6) Sold under the reference ARALDITE HY 917 by Ciba-Geigy;

(7) Sold under the reference ARALDITE DY 070 by Ciba-Geigy;

(8) Sold under the reference SYNOLIT 1717 by DSM;

(9) Sold under the reference HTM 60 by Ciba-Geigy;

(10) Sold under the reference POLYGLYCOL 1000 by Clariant;

(11) Sold under the reference TOLONATE HDB LV by Rhodia;

(12) Sold under the reference SIMULSOL P4 by Seppic;

(13) Sold under the reference PolyBd-diamine by Atofina. 

1. A glass strand coated with a sizing composition consisting of a solution comprising less than 5% by weight of solvent and comprising a curable base system, said system comprising at least 50% by weight of a mixture of: one or more components comprising at least one isocyanate reactive functional group; one or more components comprising at least one hydroxyl reactive functional group; and optionally, one or more components comprising at least one amine reactive functional group.
 2. The glass strand as claimed in claim 1, wherein the curable base system represents 60 to 100% by weight of the composition.
 3. The glass strand as claimed in claim 2, in that wherein the base system represents 75 to 90% by weight of the composition.
 4. The glass strand as claimed in claim 1, wherein the base system consists of 75% and up to 100% by weight of one or more isocyanate components, one or more hydroxyl components and one or more amine components.
 5. The glass strand as claimed in claim 1, wherein the base system comprises at least 70% by weight of one or more components of molecular mass less than
 750. 6. The glass strand as claimed in claim 1, wherein the ratio r of the number of isocyanate reactive sites to the number of hydroxyl reactive sites is between 0.1 and
 6. 7. The glass strand as claimed in claim 1, wherein the ratio r′ of the number of isocyanate reactive sites to the sum of the number of hydroxyl reactive sites and of the number of amino reactive sites is between 0.1 and
 6. 8. The glass strand as claimed in claim 1, wherein the content of isocyanate component(s) is between 10 and 50%, by weight of the sizing composition.
 9. The glass strand as claimed in claim 1, wherein the content of hydroxyl component(s) is between 15 and 55%, by weight of the sizing composition.
 10. The glass strand as claimed in claim 1, wherein the content of amine component(s) is less than or equal to 30%, by weight of the sizing composition.
 11. The glass strand as claimed in claim 1, wherein the composition comprises from 0 to 5% by weight of a catalyst.
 12. The glass strand as claimed in claim 1, wherein the composition comprises from 0 to 30% by weight of a coupling agent.
 13. The glass strand as claimed in claim 1, wherein the composition comprises from 0 to 30% by weight of a textile processing aid.
 14. The glass strand as claimed in claim 1, wherein the base system consists of one or more isocyanate components comprising at least two isocyanate reactive functional groups, one or more hydroxyl components comprising at least one hydroxyl reactive functional group and, optionally, one or more amine components comprising at least one amine reactive functional group.
 15. The glass strand as claimed in claim 14, wherein the base system consists of one or more isocyanate components comprising three isocyanate reactive functional groups and one or more hydroxyl components comprising one to three hydroxyl reactive functional groups.
 16. The glass strand as claimed in claim 14, wherein the base system consists of one or more isocyanate components comprising three isocyanate reactive functional groups, one or more hydroxyl components comprising a hydroxyl reactive functional unit and one or more amine components comprising two primary amine reactive functional groups.
 17. A sizing composition, consisting of a solution comprising less than 5% by weight of solvent and comprising a curable base system, said system comprising at least 50% by weight of a mixture of: one or more components comprising at least one isocyanate reactive functional group; one or more components comprising at least one hydroxyl reactive functional group; and optionally, one or more components comprising at least one amine reactive functional group.
 18. A composite comprising at least one organic and/or inorganic material and sized glass strands, wherein all or some of the glass strands comprises the glass strand as claimed in claim
 1. 19. (canceled)
 20. A method for forming a cloth, said method comprising forming said cloth which comprises said glass strand as claimed in claim
 1. 